Radio selection

Pat at Aquataur tells me he uses a Hitec Laser 6 radio. In the US, such a
radio with a receiver and a couple of servos is sold as a package for about $135.
But it's a shame to do this because the Laser 6 appears to over-kill. It
has six channels, two 2-axis joysticks, and ATV on three channels (ATV and EPA
features let you electronically constrain the range of motion of a servo).
Let's look at the actual requirements:

Hitec Laser 6

Hitec Ranger III FM

Feature

Any sailboat

A600

Surface Frequency

X

X

Two 1-axis joysticks or one 2-axis joystick

X

X

3rd channel

maybe

X

3rd channel: proportional (not just On-Off)

maybe

X

3rd channel: ATV or EPA

maybe

X

Ability to manipulate all 3-channels at once *

no

X

* which rules out a knob on top of the radio for the 3rd channel

As you can see, the requirements for the A600 are quite beyond most sailboat
requirements. The selection of radios for surface use (as opposed to aircraft)
are already somewhat limited. Cars and boats just don't have the demands that
airplanes do.

I did find one alternative, the
HiTec Ranger III FM can be bought for $70. It has 3-channels with the ATV feature
on two. It's two joysticks control Channels 1 and 2, with a slider on top for
Channel 3. Since only 1 & 2 have the ATV feature required for the winches, you
would have to put the rudder on the top slider, which is an odd set-up for boat radios.

I did some research and found that the ATV feature is relatively simple to add to
most modern radios. You simply add a small variable resistor, known as a "trimmer
potentiometer", in line with the center lug of the joystick. You'll have to break
into your radio and void the warranty to make this modification. The value of the
potentiometer varies from radio to radio. For the Ranger III I came up with a value
of 50K ohms by trial and error. The fix is shown below:

You must drill a small hole in the back of the case and glue the blue potentiometer
over the hole. You can see the center leg of the potentiometer connected to the radio,
and another leg connected to the slider. The other leg of the potentiometer is not used.
The potentiometer I used is from
Jameco Electronics, although you
may find alternatives at a local electronics supply store. Ask for a "50k trim pot".

Remember that this particular value resistor is what worked for the Hitec Ranger III,
other radios have different values. You adjust the potentiometer with a small
screwdriver through the back of the radio. At it's most clockwise position, it has
no effect; at it's most anti-clockwise it reduces the servo travel by 20% or so.

Configuration

Here's how Pat at Aquataur sets up his Hitec Laser 6:

Right Stick: rudder and sailLeft Stick: crewman

Here's how I'm setting up my Hitec Ranger III:

Right Stick: rudderLeft Stick: crewmanTop slider: sail

Lastly let me quote Aquataur's Pat Clear:

I use the Hitec Laser 6 as it has ATV on all channels including
number 4. I would STRONGLY recommend the use of a radio with two
gimballed sticks for ease of sailing.